how do I send mouseclick to combobox?

Cantona213

I have dynamic comboboxes ( when I select from combobox1, combobox2 is populated ). I am trying to send, from another application, a mouseclick to combobox1, so that it registers a SelectedIndexChanged event.

How do I use sendmessage to send a mouseclick to combobx? I tried WM_LBUTTONDOWN and WM_LBUTTONUP, but, it doesn't work correctly?

thanks in advance